Are there wildcards for use with the switch expression/statement in Ceylon?

Question

The title is my question. Specifically, wildcards are important when matching against values in tuples.

In OCaml it is possible:

match x with 
   (3, _) -> 5 | 
   (_, 4) -> 7 | 
   (4, 5) -> 6;;

A 'switch' contruct, that allows matching against tuple values without wildcards is not useful. In Ceylon, I think the switch is broken ;-).

score 1 · Answer 1 · answered Jul 15 '17 at 12:53

1

No, this is not yet possible. You can match a tuple literal (case ([1, 2])), and you can use destructuring (case ([Integer i, Integer j]), which is just syntax sugar for case (is [Integer, Integer]) { value [i, j] = x; … }), but you can’t use literal values to match in a destructuring pattern.

answered Jul 15 '17 at 12:53

Lucas Werkmeister

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Is it planned to implement the same functionality as in ocaml's pattern matching? – Malelago Jul 15 '17 at 14:20
I’m not sure; I remember there were some discussions about it, but none of the currently open issues I could find seem to cover something like `case ([1, x])` or `case ([1, Integer x])`. – Lucas Werkmeister Jul 15 '17 at 17:38
2

Right, we do plan to eventually allow stuff like `case ([1, x])`. – Gavin King Jul 18 '17 at 18:00

Are there wildcards for use with the switch expression/statement in Ceylon?

1 Answers1